Human adenovirus 12 is being successfully used to produce a unique animal model of retinoblastoma, one of the most common children's cancers of the eye. Direct intraocular inoculation of highly concentrated virus fluid cultivated in HeLa cell or Human Embryo Kidney (HEK) cell line leads newly born animals (CD, CDF rats, and C3H/BifB/Ki inbred mice) to bear solid retinoblastoma-like new growth at approximately 50 per cent incidence. Lower incidence is expected in pure strain mice (15.5%). Immunofluorescence microscopic detection of adenovirus-specific tumor neoantigens within the vast majority of the retinoblastoma-like tumor cells enables us to suggest that at least part of the virus genome is being incorporated into the malignantly transformed retinal cells and conveyed perpetually from the primary culture line to its progeny. Electron microscopic identification of the adenovirus-produced retinal tumor cells implies that human retinoblastoma cells are hardly distinguishable from the virus-induced retinal tumors. Cultured tumor cell explants stemmed from both CDF inbred albino rats and C3H/BifB/Ki mice are subjected to identification for the unique surface antigenicity and other molecular biochemical characteristics. Attempts are being made to duplicate the same tumor phenotype in olive baboon babies, and thereby carry out the DNA-RNA hybridization procedure to pinpoint the viral genome in human retinal cancer cells. BIBLIOGRAPHIC REFERENCES: Mukai, N.: Human adenovirus-induced embryonic neuronal tumor phenotype in rodents. In Zimmerman, H.M. (ed.): Progress in Neuropathology, vol. III, chap. IV. New York, Grune and Stratton, 1976, pp. 89-128. Mukai, N., Freddo, T., and Nakajima, T.: An assessment of the generation times of neuronal precursors in the sensory retina and subventricular zone of the newborn rat. Can. J. Ophthalmol. 11:223-228, 1976.